Device for injecting hot gases into a shaft furnace

ABSTRACT

The device has a longitudinal unit comprising an outer metal tube and an inner refractory tube. A liquid-cooled nozzle at one end of the unit converges to a narrow outlet. A terminal element at the other end of the unit serves to connect the device to the outer furnace wall, to connect the bore of the longitudinal unit to a hot gas supply, and to connect the device to a cooling liquid supply.

United States Patent [191 Ponghis et al.

DEVICE FOR INJECTING IIOT GASES INTO A SHAFT FURNACE Inventors: Nicolas Gerassimos Ponghis; Claude Henri Vanosmael, both of Liege, Belgium Assignee: Center De Recherches MetaIlurgiques-Centrum Voor Research In De Metallurgie, Brussels, Belgium Filed: Nov. 30, 1972 Appl. No.: 310,798

Foreign Application Priority Data 9 Nov. 30, 1971 Belgium 776093 us. CI. .L 266/41 Int. Cl C21b 7/16 Field of Search 266/34. L, 41; 110/1825;

[451 Feb. 26, 1974 [56] References Cited UNITED STATES PATENTS White 266/41 Primary ExaminerGerald A. Dost Attorney, Agent, or Firm-Holman & Stern' [57] ABSTRACT The device has a longitudinal unit comprising an outer metal tube and an inner refractory tube A liquidcooled nozzle at one end of the unit converges to a narrow outlet. A terminal element at the other end of the unit serves to connect the device to the outer furnace wall, to connect the bore of the longitudinal unit to a hot gas supply, and to connect the device to a cooling liquid supply.

21 Claims, 2 Drawing Figures DEVICE FOR INJECTING HOT GASES INTO A SHAFT FURNACE The present invention relates 'to an injection device for injecting into a shaft furnace (particularly'a blast furnace) hot gases of a reducing nature for preference, such as gases mainly containing CO and/or H and/or hydrocarbons, these gases being liable moreover in particular to contain CO and/or H O and/or N To perform injections of this kind in satisfactory conditions, the devices employed should be able to withstand temperatures of the order of 1000C to l250C, to give rise to only small heat losses and to be gas-tight.

Another condition which must also be fulfilled by these devices is that of ensuring a regular and uniform penetration of the hot gases into the shaft furnace. To

this end, these devices should have a quite specific internal profile. However, when the gases to be injected contain reducing gases in particular, such as CO and H and are at high temperature, the material forming these injection devices is in contact with a very corrosive environment, which this material has to be able to withstand chemically and mechanically, failing which the internal profile of the devices runs the risk of undergoing rapid deterioration with the consequent appearance of fluid flow impairment in these devices and impairment of the penetration into the shaft furnace.

The result of these considerations is that the conventional tuyeres employed until now in shaft furnaces and in particular in blast furnaces, cannot be appropriate for the injection of such hot gases, and that a new kind of device should be adopted.

The present invention provides a device for injecting hot gases into a shaft furnace, the device comprising:

a. a longitudinal unit comprising two co-axial tubes, the outer tube being of a metallic substance having satisfactory mechanical strength and chemical resistance at high temperature, and the inner tube being of non-metallic refractory substance and having a central bore of constant'diameter and an internal surface of uniform smoothness;

b. a terminal liquid-cooled nozzle extending the longitudinal .unit and constituting an outlet for the hot gases to be injected, the internal bore of the nozzle having a convergent portion followed by a parallelsided neck;

c. a terminal element on the end of the longitudinal unit opposite to the nozzle, the terminal element comprising a collar adapted for fastening to the outer wall of a shaft furnace, and a connector adapted to connect the bore of the longitudinal unit to a hot gas supply and having an inlet and an outlet for circulation of cooling liquid; and

d. a cooling liquid circulation circuit.

It has proved to be an advantage for the metallic substance forming the outer tube of the longitudinal unit to consist of alloy steel or so-called special steel, preferably stainless steel.

For the purpose of ensuring the presence of a uniformly smooth surface within the central tube of the longitudinal unit, the non-metallic substance forming this tube advantageously consists of a very fine-grained castable refractory concrete posessing considerable restance as that of the outer tube of the longitudinal unit, -or a metallic substance possessing high thermal conductivity, preferably copper. Also the collar of the terminal element (preferably an annular flange), intended for fastening to the outer wall of the shaft furnace advantageously consists of a metallic substance, possibly being the same as that forming the outer tube of the longitudinal unit. This collar may form anextension of the outer tube of the longitudinal element to which it is secured by means of a frustoconical connecting piece, also consisting of metal, and by appropriate connections, for example welded joints.

The connector or thicker part of the annular flange or terminal element may consist of a non-metallic refractory substance, preferably being the same as that of the inner tube of the longitudinal unit, of which it forms the extension and, in this preferred case, with which it forms a single piece. The thicker part of the annular flange may alternatively consist of a metallic substance and forms a single piece with the collar.

The water or the cooling liquid circulation circuit may advantageously comprise, on the one hand, a water inlet and a water outlet which are situated at the periphery of the annular flange and, on the other hand, a circular part in the said annular flange, a rectilinear part traversing the longitudinal unit and a terminal part formed by the circuit appertaining to the nozzle extending the longitudinal unit.

The circular part of the water circulation cooling circuit situated within the annular flange advantageously comprises two separate annular chambers of whichone is intended to be connected to a water feed pipe and of which the other is intended'to be connected to a water discharge pipe, the connection between the first and second chambers consisting of the rectilinear part of the circuit traversing the longitudinal unit and of the terminal circuit appertaining to the nozzle.

The circular part of the water circulation cooling circuit situated within the annular flange may be independent of the other two parts, evidently having a water inlet and outlet which are also separate.

The rectilinear part of the water circulation cooling circuit traversing the longitudina element advantageously consists of pipes partially housed within the thickness of the wall of the outer tube and partially within the thickness of the wall of the inner tube, two pipes which are intended for the outward flow, are diametrically opposed and displaced through with respect to the two pipes intended for the return flow, preferably being incorporated.

The application of other structural forms in combination with the device described above, for example to ensure optimum sealing of the injection system, does not lie outside the scope of the present invention. it is possible 'for this purpose,for a joint acting as a packing and consisting of a refractory material which is pliable and resistant to high temperatures, for example suchas mineral wool, to be positioned between the nozzle and the wall of the shaft furnace, to allow free movement of the set of refractory units of the furnace during the different thermic cycles, on the one hand, and for appropriate sealing joints to be positioned between the casing of the blast furnace and the nozzle as well as between the feed piping system and the nozzle, on the other hand. 1 I

The invention will be described further, by way of example only, with reference to the accompanying drawings, in which:

F 1G. 1 is a longitudinal section through a hot gas injection device mounted in the wall of a blast furnace; and

FIG. 2 is a transverse section through the device.

This injection device comprises a longitudinal unit 1, a terminal nozzle 2 extending the unit 1, a terminal element 3 at the other end of the unit, and a water circulation cooling circuit.

The longitudinal unit 1 consists of two co-axial tubes 4 and 5. The outer tube 4 is of stainless steel possessing satisfactory mechanical strength and chemical resistance at high temperatures. The inner tube 5 lines the tube 4 and has a central bore 6 of constant diameter and an internal surface of uniform smoothness. To this end, it consists of a very fine-grained castable refractory concrete also possessing great strength at high temperatures.

The nozzle 2, intended to form the outlet for the hot gases to be injected, is in the form of a conventional tuyere of the type employing cooling by circulation of water. The internal profile of this nozzle comprises a convergent part 7 followed by a parallel-sided neck 8. The nozzle consists of copper to ensure satisfactory heat transmission and is secured to the outer tube 4 by means of a welded joint 9.

The terminal element 3 consists of two parts a collar or annular flange 10 and a connector 11 which are joined to each otherl The flange 10 is fastened to the outer wall of the shaft furnace and is made of the same stainless steel as that of the outer tube 4 of which it forms an extension. This annular flange 10 is fastened to the outer tube 4 by means of a frustoconical connecting piece 12, of the same material, by welded joints l3 and 14. The connector 11, which is thicker than the flange 10 is connected to the feedpiping system of the hot gases to be injected, and also contains a cooling circuit. This connector 11 is made of the same nonmetallic refractory substance as the inner tube 5, of which it forms an extension and with which it forms a single piece.

The cooling circuit whose inlet 15 and outlet 16 are situated at the periphery of the terminal element 3, comprises a circular part within the terminal element, a rectilinear part traversing the longitudinal unit 1, and

a terminal part consisting of the'circuit appertaining to the copper nozzle 2. The part of the circuit situated within the terminal element 3 comprises two separate annular chambers 17 and 18, of which one 17 is connected to a water feed pipe 19 and of which the other 18 is connected to a water discharge pipe 20. The connection between the chambers 17 and 18 and the rectilinear part in the longitudinal unit 1 is by means of elbow pipes 21 and 22 housed within the refractory material of the connector 11. The rectilinear part of the water circulation cooling circuit traversing the longitudinal unit 1 consists of pipes 23 and 24 partially housed within the thickness of the wall of the outer tube 4 and partially within the thickness of the wall of the inner tube 5. There are two pipes 23. for outward flow of the nozzle, being diametrically opposed and displaced through 90 with respect to the two pipes 24 intended for the return flow. The circuit appertaining to the nozzle 2 receives water from an extension 25 of the outward pipes 23 and discharges water to an extension 26 4 of the return pipes 24. The pipes 21 to 26 are of stainless steel.

We claim:

1. A device for injecting hot gases into a shaft furnace, the device comprising:

a. a longitudinal unit comprising two co-axial tubes, the outer tube being of a metallic substance having satisfactory mechanical strength and chemical resistance at high temperatures, and the inner tube being of non-metallic refractory substance and having a central bore of constant diameter and an internal surface of uniform smoothness;

b. a terminal liquid-cooled nozzle extending in the longitudinal unit and constituting an outlet for the hot gases to be injected, the internal bore of the nozzle having a convergent portion followed by a parallel-sided neck.

0. a terminal element on the end of the longitudinal unit opposite to the nozzle, the terminal element comprising a collar adapted for fastening to the outer wall of a shaft furnace, and a connector adapted to connect the bore of the longitudinal unit to a hot gas supply and having an inlet and an 7 outlet for circulation of cooling liquid, and

d. a cooling liquid circulation unit.

2. A device as claimed in claim 1, wherein the metallic substance of the outer tube is an alloy steel.

3. A device as claimed in claim 2, wherein the alloy steel is stainless steel.

4. A device as claimed in claim 1, wherein the nonmetallic substance of the inner tube is a fine-graded castable refractory concrete possessing great strength 1 at high temperature.

5. A device as claimed in claim 1, wherein the nozzle is made of the same metallic substance as that ofthe outer tube of the longitudinal unit.

6. A device as claimed in claim 1, wherein the nozzle is made of a metallic substance possessing high thermal conductivity.

7. A device as claimed in claim 6, wherein the-nozzle is made of copper.

8. A device as claimed in claim 1, wherein the collar of the terminal element is made of a metallic substance.

9. A device as claimed in claim 8, wherein the collar is made of the same metallic substance as that of the outer tube of the longitudinal unit.

10. A device as claimed in claim 8, wherein the collar is secured to the outer tube by means of a frustoconical connecting piece made of metal.

11. A device as claimed in claim 1, wherein the connector of the terminal element is made of a nonmetallic refractory substance.

12. A device as claimed in claim 11, wherein the connector is made of the same non-metallic refractory substance as that of the inner tube of the longitudinal unit.

13. A device as claimed in claim 11, wherein the connector forms an extension of the inner tube of the longitudinal unit. a

14. A device as claimed in claim 13, wherein the connector is in a single piece with the inner tube.

15. A device as claimed in claim 1, wherein the connector of the terminal element is made of a metallic substance.

16. A device as claimed in claim 15, wherein the conand a liquid outlet on the periphery of the terminal element, a circular part within the terminal element, a rectilinear part traversing the longitudinal unit, and a terminal part in the nozzle.

18. A device as claimed in claim 17, wherein the circular part of the cooling circuit comprises two separate annular chambers, one connected to the liquid inlet and the other connected to the liquid outlet, the first and second chambers being connected by the rectilinear part of the circuit traversing the longitudinal unit and the terminal circuit of the nozzle.

19. A device as claimed in claim 17, wherein the circular part of the cooling circuit is independent of the 

1. A device for injecting hot gases into a shaft furnace, the device comprising: a. a longitudinal unit comprising two co-axial tubes, the outer tube being of a metallic substance having satisfactory mechanical strength and chemical resistance at high temperatures, and the inner tube being of non-metallic refractory substance and having a central bore of constant diameter and an internal surface of uniform smoothness; b. a terminal liquid-cooled nozzle extending in the longitudinal unit and constituting an outlet for the hot gases to be injected, the internal bore of the nozzle having a convergent portion followed by a parallel-sided neck. c. a terminal element on the end of the longitudinal unit opposite to the nozzle, the terminal element compriSing a collar adapted for fastening to the outer wall of a shaft furnace, and a connector adapted to connect the bore of the longitudinal unit to a hot gas supply and having an inlet and an outlet for circulation of cooling liquid, and d. a cooling liquid circulation unit.
 2. A device as claimed in claim 1, wherein the metallic substance of the outer tube is an alloy steel.
 3. A device as claimed in claim 2, wherein the alloy steel is stainless steel.
 4. A device as claimed in claim 1, wherein the non-metallic substance of the inner tube is a fine-graded castable refractory concrete possessing great strength at high temperature.
 5. A device as claimed in claim 1, wherein the nozzle is made of the same metallic substance as that of the outer tube of the longitudinal unit.
 6. A device as claimed in claim 1, wherein the nozzle is made of a metallic substance possessing high thermal conductivity.
 7. A device as claimed in claim 6, wherein the nozzle is made of copper.
 8. A device as claimed in claim 1, wherein the collar of the terminal element is made of a metallic substance.
 9. A device as claimed in claim 8, wherein the collar is made of the same metallic substance as that of the outer tube of the longitudinal unit.
 10. A device as claimed in claim 8, wherein the collar is secured to the outer tube by means of a frustoconical connecting piece made of metal.
 11. A device as claimed in claim 1, wherein the connector of the terminal element is made of a non-metallic refractory substance.
 12. A device as claimed in claim 11, wherein the connector is made of the same non-metallic refractory substance as that of the inner tube of the longitudinal unit.
 13. A device as claimed in claim 11, wherein the connector forms an extension of the inner tube of the longitudinal unit.
 14. A device as claimed in claim 13, wherein the connector is in a single piece with the inner tube.
 15. A device as claimed in claim 1, wherein the connector of the terminal element is made of a metallic substance.
 16. A device as claimed in claim 15, wherein the connector is in a single piece with the collar.
 17. A device as claimed in claim 1, wherein the cooling liquid circulation circuit comprises a liquid inlet and a liquid outlet on the periphery of the terminal element, a circular part within the terminal element, a rectilinear part traversing the longitudinal unit, and a terminal part in the nozzle.
 18. A device as claimed in claim 17, wherein the circular part of the cooling circuit comprises two separate annular chambers, one connected to the liquid inlet and the other connected to the liquid outlet, the first and second chambers being connected by the rectilinear part of the circuit traversing the longitudinal unit and the terminal circuit of the nozzle.
 19. A device as claimed in claim 17, wherein the circular part of the cooling circuit is independent of the remaining parts, having a water inlet and outlet which are also separate.
 20. A device as claimed in claim 1, wherein the cooling circuit traverses the longitudinal unit and comprises pipes partially housed within the thickness of the wall of the outer tube and partially within the thickness of the wall of the inner tube.
 21. A device as claimed in claim 20, wherein there are four pipes equally spaced around the inner tube, one pair of diametrically opposed pipes being inlet pipes, the other pair being outlet pipes. 